Just want to touch one a few things. Eckhart and (to a strangely even larger extent) Christian Bale are being brushed aside or nearly omitted from many reviews. They are understandably being overshadowed by Ledger. But, they still are very good in this.
Eckhart has to be the white knight. Bruce Wayne has to come to love and trust this man on some level. He's important to Batman in very real ways.
In an interview, Bale described the way he's approaching Batman. He's not just doing the traditional Bruce/Batman role. He's approaching it as Bruce/Batman/Bruce. Instead of the silly guy in the suit, it's his two Bruce's where he's strongest. His layered performance is not only able to switch between both at will, but he can effectively play them both at once.